So sorry you are dealing with thrush. What did your doc call-in for you? In my experience, the Nystatin treatment was completely useless. My LC told me that around 60% of thrush is now resistant to Nystatin, which is probably why it didn't work for us. Here's the protocol that finally got the yeast cleared-up for us:
1. Paint nips and LO's mouth with Gentian Violet. It is available over-the-counter, but you have to ask for it.
2. Daily good-quality probiotics (from the local health food store) for LO and me.
3. Rx diaper cream for LO's bottom to kill the yeast there.
4. Daily sanitizing of anything that came in contact with my breasts, BM, or LO's mouth (bras, pump parts, pacis, bottles, etc.). For bras, hand-wash in hot water, with detergent and white vinegar, then line-dry in direct sunlight.
5. Max dose of Grapefruit seed extract (also from the health food store)
6. Cut all refined flour and sugar out of my diet.
7. Use of All Purpose Nipple Ointment (APNO) by Dr. Jack Newman. It really helped with pain and encouraged healing.
Here is a link to Dr. Newman's Candida Protocol, including the recipe for APNO. DD and I eventually had to take a 10-day course of Diflucan, because we had thrush for almost 3-4 mo. I finally figured out that we were being re-infected by a paci storage container that they used at daycare (they washed it, but did not sanitize it).
I hope you get well soon!